Antibodies against estriol 16-glucuronate and estetrol (15 alpha hydroxyestriol) will be generated in sheep using antigens prepared by coupling each estrogen to bovine serum albumin through carbon-6. This will first require preparation of the 6-oxy derivatives of estriol 16-glucuronate and estetrol as outlined in our proposed route of synthesis. The antibodies generated against these steroid haptens will be separated from the crude antiserum using a novel fractionation procedure to achieve maximum sensitivity for assay purposes. The estriol 16-glucuronate antibody fraction will be used in a rapid latex agglutination test for this conjugate in urine, in order to assess fetal well-being in high-risk pregnancy patients. The estetrol antibody fraction will be used to devise a radioimmunoassay for this estrogen in plasma so as to determine its clinical potential as an aid in managing certain problem pregnancies.